We propose to investigate the social behaviour of the Laughing Gull, with special attention to communication and social development, and individual recognition. Data from field observations, motion pictures, and tape recording will be subject to situation and sequence analysis and analysis for individual characteristics. Individual identification and other communication functions will be experimentally investigated, using playback of recordings and other techniques. Developmental aspects of social communication will be studied by observation of free-living and captive young, and by manipulation of early experience. Data will also be collected relevant to the question of how features of the breeding behaviour of the gulls, and other species inhabiting the salt-marsh, answer to the ecological pressures of this habitat, especially that imposed by tidal flooding.